The present invention relates to a system by which a human operator of a remote unmanned vehicle is provided sensory inputs relating to the operating characteristics of the vehicle. More specifically, the present invention provides a system by which the human operator of an unmanned vehicle is able to sense the speed of the moving vehicle without having to read a visual indicator.
The use of remotely operated vehicles in applications such as material and inventory control in manufacturing environments is increasing and becoming ever more sophisticated. Recent advances in technology have brought about an even greater interest for their use in hazardous environments, such as nuclear power plants, underwater search and recovery, fire-fighting, and bomb disposal, to name a few. Often, however, the advantages afforded by removing the operator from a hazardous environment are significantly offset by the difficulties encountered in controlling the remote vehicle. This limits the types of practical applications of remotely controlled robots to those for which the perils associated with direct exposure justify the expense and complexity of the remote system.
A considerable amount of work has been done over the past decade to improve the man-machine interface for teleoperated (remotely controlled) systems in an attempt to achieve a higher operational equivalence ratio. The operational equivalence ratio may be defined as the amount of time it takes to perform a series of tasks, divided by the amount of time it would take an operator to perform the same tasks remotely.
Some recent applications involving remote control systems employ a concept of remote telepresence, which utilizes stereo vision as well as binaural hearing to give the operator a stronger sense of being in the working environment. Head-coupled displays have been employed to further enhance this perception. A pair of high-resolution cameras on a remotely controlled vehicle are positioned in real-time in accordance with the pan and tilt movements of a helmet worn by the operator at the control station. The helmet is equipped with miniature monitors to relay the video from the left and right cameras to the left and right eyes of the operator, thus providing some degree of depth perception.
As the operator turns his head toward elements of interest in the scene being viewed, the remote slave positions the cameras accordingly to achieve the desired input. The 3-D capability thus provided is a decided improvement over monocular vision. However, its negative side effects include extremely high operator fatigue, tendency to induce nausea in some operators, higher bandwidth requirements in the control loop and significantly enhanced system complexity. In most remote systems in use today, the operator's only sense of vehicle speed is derived from the visual display alone and this can lead to problems if the operator is distracted from looking at the display.
A block diagram of a typical commercially available remotely controlled unmanned vehicle, such as the TRC Labmate, or Cybermotion NavMaster, is illustrated in FIG. 1. In this type of system, a human operator controls unmanned vehicle system 10, comprised of different subsystems that include servo-controlled drive module 12, from an operator interface 14 which could be a computer work station 11 that typically includes one or more data input devices such as a keyboard or joystick, and a display such a video monitor, not shown. Control data provided by the operator is received by host computer 16 which transmits operating instructions to drive module 12 through a data link 18 which could be an RF link or a data bus. The operating instructions are received by a remote computer 20 mounted onboard remote vehicle 10. Remote computer 20 coordinates the different systems that may be onboard unmanned vehicle 10, including drive module 12. Data representing the operating characteristics of vehicle 10 is conveyed back to operator interface 14 through remote computer 20 via data link 18, to host computer 16 and is displayed by a video monitor which is part of operator interface 14.
A fundamental consideration in the design of a remotely operated system is the ability of the operator to control the vehicle based on system status feedback received from the vehicle. The primary source of feedback used by an operator when driving a typical remotely operated vehicle is a visual image received from a camera that surveys the vehicle's operating environment. The visual image of the operating environment displayed on the video monitor, however, cannot provide the same degree of depth perception or visual acuity that an operator seated in the vehicle would have, even with the more advanced stereo tele-presence systems. The performance of the vehicle is therefore degraded. Other types of useful feedback information, such as vehicle speed and heading, are typically overlaid on this same video monitor. However, safe operation of the vehicle in such a situation, where the operating characteristics of the vehicle are displayed on a video monitor, requires constant vigilance by the human operator in reading the data display presented on the video monitor. A disadvantage of this type of data presentation is that if the operator should become distracted or fatigued, the safe operation of the vehicle may be compromised.
For example, the operator may attempt to provide a halt instruction to the vehicle, but the instruction may not be faithfully executed for any variety of reasons, which could include the vehicle rolling down a hill in neutral, or a the failure of the vehicle brakes. The actual vehicle speed might be displayed on the video monitor, but the operator may not be expecting the need to pay attention to it. Another foreseeable circumstance in which the operator is not cognizant of the vehicle speed would be if the operator became distracted, or where it was assumed that the intended instruction was fulfilled without confirmation by reading the video display.
Therefore, there is a need for a feedback system which provides non-visual feedback of the actual vehicle speed so that the operator is not required to focus his attention on a dedicated vehicle speed display representation.